Automatically movable irrigation systems have been employed for a considerable period of time for the purpose of irrigating land areas under conditions where rainfall is insufficient for optimum growing of crops. One example of a tower-supported movable irrigation system which, in this case, is movable in circular manner about a central supply pivot is depicted in U.S. Pat. No. 3,608,826. It should be noted that this patent depicts a water-carrying conduit structure made up of several sections of irrigation pipe that are coupled by a universally movable coupling. A boot is employed to contain the water pressure and prevent leakage during operation of the system. Where movable wheeled tower-supported irrigation systems are employed, in some cases the speed of rotation or speed of movement of each of the sections of irrigation pipe is controlled by a single speed electric motor that is intermittently energized and de-energized responsive to the particular angular relationship between the various pipe sections that make up the water supply conduit of the irrigation system. The eletric drive motor, together with its reduction gear mechanism, will remain de-denergized until the horizontal angular relationship between sections of the irrigation pipe reaches a predetermined value responsive to movement of adjacent towers of the irrigation system. Upon reaching the predetermined relationship, the electric drive motors will become energized, thus moving the tower associated therewith sufficiently to develop another predetermined horizontal angular relationship between the pipe sections involved, at which time the motor will be de-energized. This feature eliminates the need for expensive motor drive systems of varying speed for each of the pipe sections that revolves about the central pivot point and further enhances the competitive nature of irrigation systems that are constructed in this manner.
As tower-supported irrigation systems move during irrigation of land areas, changes in grade occur due to unevenness of the land surface. It is necessary that the various pipe sections that interfit to transport water from the water supply to the various parts of the irrigation system be capable of vertical movement to accommodate changes in grade, as well as accommodating horizontal angular misalignment responsive to tower movement. It is therefore desirable to provide coupled irrigation pipes with a pipe coupling that efficiently allows universal movement of the connected pipe sections so as to prevent the development of any strain that might otherwise cause deterioration of the connection structure between the various pipe sections.
As the angular relationship between the various pipe sections of the irrigation system changes during irrigation operations, it is of course necessary that the coupling structure establishing connection between the pipe sections be allowed to freely articulate. It is also necessary, however, that the coupling structure include a sealing element that prevents leakage of the coupling during the universal articulation that occurs as the irrigation system negotiates uneven terrain during its operation. The boot structure of U.S. Pat. No. 3,608,826 is one suitable means for preventing leakage and yet allowing articulation at the coupling connection between the pipe sections.
It is well known in the art to utilize spherical couplings for establishing articulated connection between sections of irrigation pipe, such as shown by U.S. Pat. No. 1,949,055 to Lambie and U.S. Pat. No. 2,281,633 to Stitzer and U.S. Pat. No. 2,652,282 to Willetts. Because of the spherical shape of the coupling structure, the only practical way the coupling structure can be disassembled for replacement of a seal is for the pipe sections to which the coupling structure is affixed to be moved linearly apart. In irrigation systems of considerable length, it may be impractical or at least highly undesirable to move the irrigation pipes linearly apart because to do so could require special heavy-duty lifting apparatus. It is desirable, therefore, to provide a pipe coupling structure for irrigation pipes that can be dissembled for replacement of a seal simply by partial disassembly without relative linear movement of adjacent sections of irrigation pipe.
Where irrigation pipes are supported by mobile towers, it is typical for each extremity of each of the various spans of irrigation pipe to be physically supported by the mobile tower devices or by load-supporting devices that are in turn supported by the mobile towers. The irrigation pipe sections defined by the various spans of the irrigation system must be supported in such manner that the extremities thereof will be positively aligned. Such support structures for the pipe sections are typically quite expensive and serve to detract from the commercial feasibility of the irrigation system.
As tower-supported irrigations systems move about land areas during irrigation operations, it is known that severe tensile and compressive forces are exerted on coupled pipe sections, thereby requiring that the pipe couplings be quite heavy and strong to prevent the couplings from being pulled apart. It is desirable that a spherical coupling structure be provided that is capable of withstanding severe tensile loads and yet remain free for universal movement as the pipe sections articulate during irrigation operations.
Accordingly, it is a primary object of the present invention to provide a novel universally movable coupling for irrigation pipe, which coupling incorporates a sealing element that may be simply and efficiently replaced in the event it should become worn to the point that it does not seal properly.
It is another feature of the present invention to provide a novel universally movable coupling structure having a spherical-type connection for allowing free universal movement in all directions.
It is also a feature of the present invention to provide a novel spherical coupling structure that may also incorporate a pivot pin type connection that provides for efficient resistance against tensile and compressive loads that might otherwise tend to damage or cause separation of the coupling structure during irrigation operations.
Among the several features of the present invention is noted the contemplation of a novel coupling structure for irrigation pipes incorporating means for draining the irrigation pipe sections and the coupling structure efficiently so as to facilitate simple and efficient repair or replacement of any of the parts thereof.
It is also an important feature of the present invention to provide a novel universally movable coupling structure for irrigation pipes that may be disassembled for replacement of the sealing element thereof without any requirement for linear separation of adjacent sections of irrigation pipe and which provides support for one extremity of one of the sections of irrigation pipe, both during normal irrigation operations and when disassembled.
The present invention also contemplates the provision of a novel universally movable coupling structure for irrigation pipes incorporating simple and efficient means for at least partially separating certain components of the coupling structure without the use of heavy lifting apparatus in order to facilitate simple and efficient replacement of the sealing element thereof.
Other and further objects, advantages and features of the present invention will become apparent to one skilled in the art upon consideration of the present disclosure. The form of the invention, which will now be described in detail, illustrates the general principles of the invention, but it is to be understood that this detailed description is not to be taken as limiting the scope of the present invention.